Datepicker + Moment.js months calculation (and reverse)

Datepicker + Moment.js months calculation (and reverse)

I have the following two input fields. 
In the first one there's a dropdown with the months values and on the other one i have the datepicker input box.

Using the boostrap-datepicker and moment libraries, I want to achieve the following:
1) On dropdown selection the datepicker value should change based on the month value [DONE!].
2) On date change it should check if there's the specified value of months interval in the dropdown on the left and then add the " selected" attribute on the option.

Here's the codepen link for more info:
CHECK MY CODE SO FAR

Thanks!